In the field of medicine, the endoscopic approach route has now become consolidated for performing intra-cavity operations, which offers numerous advantages over the open surgery techniques used traditionally. Endoscopy, which comprises the visual examination of a cavity or duct of the organism, is usually applied as a technique that minimizes the invasion of the patient's body cavity and is carried out by means of the insertion of an endoscope by way of a minimal surgical incision through which the sheath passes housing the instrument. The incorporation of cold light and a video camera enables therapeutic manoeuvres to be carried out in the abdominal cavity, ranging from the simple collection of a biopsy to complete operations on the organs that it contains.
In the abdomen, the introduction of the endoscope and the instruments is usually done by way of rigid or semi-rigid sheaths that pass through the abdominal wall. During the operation they facilitate the replacement of the instruments without the loss of the gas that is used to keep the cavity distended, thanks to a built-in valve system.
Similarly, in the particular case of laparoscopic surgery, i.e. that endoscopic technique used for actuation in the abdominal cavity, the use of surgical instruments is normally required for the dissection by the surgeon of anatomical spaces of loose conjunctive tissue, for which different types of tweezers and separators are also used.
The design of instruments of this type to perform a surgical operation by endoscopy is usually determined by a series of functional requirements that the instrument has to be able to fulfil, such as manipulation in the body cavity from the exterior, permitting internal actuation on organs or tissues. For this purpose, these instruments must be capable of performing a series of movements controlled by the surgeon from the exterior. The handling of the instruments in these conditions reduces the operator's manoeuvring capability since he is unable to guide the instrument grasped in his hand, making use of all the joints of his upper limb. The point of penetration of the cannula through which the instrument is inserted into the cavity restricts its movement in the same way as an oar in relation to the rowlock that secures it to the hull of the boat.
Accordingly, there is a tendency to incorporate articulated instruments that facilitate surgical manoeuvre instead of or as a supplement to traditional rigid instruments. These articulated instruments have different technical features depending on the surgery in which they are used and some of them are described below.
In U.S. Pat. No. 4,178,920, held by the institution ‘American Hospital Supply Corporation’, a urological instrument is defined that comprises a swivel element for use in cystoscopies, controlled manually by the operator, and which has a single element susceptible to be articulated for facilitating the introduction of a catheter in the mouth of a ureter. This instrument has a very limited application, since it is no use for dissection in spaces of difficult access or for those cases in which an instrument is required that simulates the movement that would be made by the surgeon's finger in open surgery operations. In addition, the articulated element is controlled directly, with no means of cushioning, so that the precision in the control of its movement is not very high, with the result that it proves rather rudimentary.
On the other hand, U.S. Pat. No. 5,366,479, applied for by the institution ‘United States Surgical Corporation’, describes another type of instrument used in endoscopy, which consists of a surgical stapler which, as in the previous case, has an area for gripping it, in the form of a handle, while coupled to this area there is a hollow rod-like element which has an articulated element at its free end that has its rotation in relation to an axis permitted in both directions. This instrument is used in surgery for applying staples, which are housed in a space in the interior of said hollow rod.
Now, although this instrument permits the rotation of the articulated element in both directions on account of its technical features and its configuration, it presents the same problems as the above-mentioned instrument, as it only permits a rotation movement of the swivel element, i.e. it only comprises one articulation and its use is limited as its purpose is strictly that of setting lines of staples in place for the occlusion of a specific segment of the digestive tube.